1. Field of the Invention
The present invention relates to a treatment instrument for an endoscope such as a clip device or biopsy forceps, and the like that is used with an endoscope having a soft insertion portion.
Priority is claimed on Japanese Patent Application No. 2006-212076, filed Aug. 3, 2006, the content of which is incorporated herein by reference.
2. Description of Related Art
Japanese Unexamined Patent Application No. H08-280701 discloses a clip device that is used with an endoscope having a soft insertion portion. In a treatment device such as the clip device, the insertion portion is formed of a tubular body that is formed of a coil of metal wire such as stainless steel, and an operation wire that is inserted in the tubular body and connected to a treatment tool that is disposed at distal end of the tubular body. A hook to which the treatment tool such as a clip unit is engaged is provided at the distal end of the operation wire via, for example, a cylindrical connecting member. The treatment tool, such as a clip unit, that is disposed or engaged at the distal end of the operation wire is activated by pulling an operating member such as the operation wire relative to the tubular body with a strong force.
To achieve a structure that facilitates operation by the operator even in the state of the tubular body being curved along the curvature of the insertion portion of the endoscope, the tubular body is constituted by a distal end side coil and a proximal end side coil being connected via a connecting portion that is harder than both. In this event, the distal end side coil is constituted to be softer than the proximal side coil. The tubular body is constituted by the proximal end portion of the distal end side coil and the distal end portion of the proximal side coil, which has a greater wall thickness and a smaller inner diameter than those of the distal end side coil, being directly connected by, for example, laser welding and the like.
As described above, in the connecting portion between the distal end side coil and the proximal end side coil, since the inner diameters mutually differ, a step arises due to the inner diameter differences at the connecting portion. For that reason, in the state of the two coils being curved into a curvature (for example, with a radius of 10 mm to 30 mm), for example, when a pulling force is impressed on the operation wire toward the proximal side during clipping of the clip unit or the like, a compressive force occurs on each coil.